/* --------------------------------
** FUNCTION:
**   fnGetFileNameExtensionFromString 
** DESCRIPTION:
**   This function extracts the file name extension
**   for a file name or a file path (with file name).
**   The extension is considered to be everything up
**   to the first 'dot' considering the file name
**   in reverse. A string containing the extension is
**   returned (or the "" empty string if there is no
**   file name extension).
** DEPENDENCIES:
**   fnReverseString
**   fnStripLeadingSpaceFromString
** SEE ALSO:
** DATE:
** 
   -------------------------------- */

function fnGetFileNameExtensionFromString(sString) 
{                                      

  //-- Verify parameters
  if (sString == null)
  {
    //-->-->-->-->-->-->-->-->-->-->-->-->
    //-- write out some nasty error message
    //-- somewhere, mortally insulting the programmer
    //-- for such a ridiculous error
    return -1;
  }

  var sReturn       = sString;
  var iIndexOfSlash = -1;
  var iIndexOfDot   = -1;

  sReturn = fnReverseString(sReturn);
  sReturn = fnStripLeadingSpaceFromString(sReturn);

  iIndexOfSlash = sReturn.indexOf("/");
  iIndexOfDot   = sReturn.indexOf(".");

  //-->-->-->-->-->-->-->-->-->-->-->-->
  //-- Cases:
  //--  1. There is no dot
  //--  2. the dot is further
  //--     away from us than the slash (remember that
  //--     we are looking at the file or url in reverse
  //--     at the moment)

  if ((iIndexOfDot > iIndexOfSlash) ||
      (iIndexOfDot == -1))
  {
    sReturn = "";
    return sReturn;
  }


  //-->-->-->-->-->-->-->-->-->-->-->-->
  //-- Cases:
  //--  1. There are no slash's
  //--   a) There is at least one dot
  //--   b) There is no dot
  //--  2. There is at least one slash
  //--   a) The dot is further away than the slash
  //--      (from a reversed point of view)
  //--   b) The dot is closer than the slash
  //--      (from a reversed point of view)

  if (iIndexOfSlash == -1)
  {
    if (iIndexOfDot != -1)   
    {
      sReturn = sReturn.substring(0, iIndexOfDot);
      sReturn = fnReverseString(sReturn);
    }
    else
    {
      sReturn = "";
      return sReturn;
    }
  }
  else
  {
    if (iIndexOfDot > iIndexOfSlash)
    {
      sReturn = "";
      return sReturn;
    }
    else
    {
      sReturn = sReturn.substring(0, iIndexOfDot);
      sReturn = fnReverseString(sReturn);
    }
  } //-- if, else (any slashes)
  return sReturn;

} //-- fnGetFileNameExtensionFromString()